Light emitting device and lighting device

Abstract

To provide a light emitting device capable of suppressing changes in light emitting characteristics caused by heat generation from a light emitting element, and a lighting device having the same.SOLUTION: A light emitting device includes: a light emitting element mounted on a substrate; a resin wall surrounding the light emitting element; a reflective resin layer provided on the substrate between the resin wall and the light emitting element; and a phosphor resin layer provided above the light emitting element, and the reflective resin layer is composed of a resin that is softer than the resin wall.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a light emitting device and an illumination device. [Background technology]

[0002] Conventionally, a light emitting device has been known in which a light emitting element and a reflective resin are stacked inside an opening in a resin wall formed on a substrate, with a phosphor layer covering them (Patent Documents 1 and 2). By using a reflective resin around the light emitting element, the light extraction efficiency is improved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 05-029665 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-055632 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional light-emitting devices such as those described above, the light-emitting elements thermally expand due to heat generation when powered on, or contract when power is switched from on to off, which can change the light-emitting characteristics of the light-emitting device.

[0005] The present disclosure has been made to solve the above problems, and aims to provide a light-emitting device that can suppress changes in light-emitting characteristics caused by heat generation in light-emitting elements, and a lighting device equipped with the same. [Means for solving the problem]

[0006] The present disclosure has been made to achieve the above-mentioned object, and provides a light-emitting device that includes a light-emitting element mounted on a substrate, a resin wall surrounding the light-emitting element, a reflective resin layer provided on the substrate between the resin wall and the light-emitting element, and a phosphor resin layer provided above the light-emitting element, wherein the reflective resin layer is made of a resin that is softer than the resin wall.

[0007] According to such a light emitting device, changes in light emitting characteristics caused by heat generation of the light emitting element are suppressed.

[0008] In this case, the reflective resin layer may be made of a resin that is softer than the phosphor resin layer.

[0009] This further suppresses changes in light-emitting characteristics caused by heat generation from the light-emitting element.

[0010] In this case, the light emitting device may have a hardness difference in Shore A hardness between the reflective resin layer and the phosphor resin layer (Shore A hardness of the phosphor resin layer - Shore A hardness of the reflective resin layer) of 0 or more and 20 or less.

[0011] This makes it possible to more stably suppress changes in light-emitting characteristics caused by heat generation from the light-emitting element.

[0012] In this case, the light-emitting element may include a light-emitting layer that generates light therein, and the upper surface of the reflective resin layer may be higher than the upper surface of the light-emitting layer and lower than the upper surface of the light-emitting element.

[0013] This further improves the brightness above the light emitting device.

[0014] In this case, the light emitting device may be one in which the reflective resin layer is made of a material that is more susceptible to hardening and shrinking due to heat than the phosphor resin layer.

[0015] This allows recesses (dents) to be formed on the upper surface of the reflective resin layer, resulting in better light-emitting properties.

[0016] In this case, the light emitting device may be one in which a recess is provided on the upper surface of the reflective resin layer.

[0017] This makes it possible to effectively suppress deterioration of light emission characteristics such as yellow ring.

[0018] In this case, the light emitting element may have a flip chip structure, and the light emitting device may be one in which the reflective resin layer and the light emitting element are in contact with each other.

[0019] This further improves the brightness above the light emitting device.

[0020] In this case, the light emitting device can be provided as a lighting device.

[0021] This results in a lighting device in which changes in light-emitting characteristics due to heat generation from the light-emitting elements are suppressed. [Effects of the Invention]

[0022] As described above, according to the light emitting device of the present disclosure, changes in light emitting characteristics caused by heat generation of the light emitting element are suppressed. [Brief explanation of the drawings]

[0023] [Figure 1] 1 shows an example of a light emitting device according to the present disclosure (cross-sectional view). [Figure 2] 10 is a cross-sectional view showing another example (modification 1) of the light emitting device according to the present disclosure. [Figure 3] 10 is a cross-sectional view showing another example (modification 2) of the light emitting device according to the present disclosure. [Figure 4] 10 is a cross-sectional view showing another example (third modification) of the light emitting device according to the present disclosure. [Figure 5] 1 shows an example of an illumination device according to the present disclosure (top view). DETAILED DESCRIPTION OF THE INVENTION

[0024] The present disclosure will be described in detail below, but the present disclosure is not limited thereto.

[0025] As described above, there has been a demand for a light emitting device that can suppress changes in light emitting characteristics caused by heat generation in the light emitting element.

[0026] As a result of extensive research into the above-mentioned problems, the inventors have discovered that a light-emitting device comprising a light-emitting element mounted on a substrate, a resin wall surrounding the light-emitting element, a reflective resin layer provided on the substrate between the resin wall and the light-emitting element, and a phosphor resin layer provided above the light-emitting element, wherein the reflective resin layer is made of a resin softer than the resin wall, can suppress changes in light-emitting characteristics due to heat generation from the light-emitting element, and have completed the present disclosure.

[0027] The following description will be made with reference to the drawings.

[0028] [Light-emitting device] First, a light-emitting device according to the present disclosure will be described with reference to FIG. 1 (cross-sectional view). As shown in FIG. 1, a light-emitting device 100 according to the present disclosure includes a light-emitting element 2 mounted on the surface of a substrate 1, a resin wall 4 surrounding the light-emitting element 2, a reflective resin layer 7 provided on the substrate 1 between the resin wall 4 and the light-emitting element 2, and a phosphor resin layer 9 provided above the light-emitting element 2. The light-emitting element 2 may have electrodes 13 and 14 bonded to a metal pattern 11 provided on the surface of the substrate 1 via a bonding layer 12 such as solder. The reflective resin layer 7 is made of a resin softer than the resin wall 4. In the present disclosure, the softness of a resin is defined by its Shore A hardness. That is, when the reflective resin layer 7 is said to be a resin softer than the resin wall 4, this means that the resin of the reflective resin layer 7 has a lower Shore A hardness than the resin of the resin wall 4. Such a light-emitting device is capable of suppressing changes in light-emitting characteristics due to heat generation from the light-emitting element.

[0029] (substrate) While the type of substrate 1 in the light-emitting device according to the present disclosure is not particularly limited, it is preferable to use a ceramic substrate as the substrate 1. Ceramic substrates have a small linear expansion coefficient compared to other practical substrates, and their temperature characteristics are similar to those of the reflective resin or other resins applied to the substrate, resulting in more stable and improved temperature characteristics for the entire light-emitting device. Because the ceramic substrate does not have a light-reflecting resist (light-reflective solder resist) applied to its surface, light emitted downward from the light-emitting element 2 is likely to transmit to the back surface of the substrate 1. Therefore, it is preferable to provide a reflective resin layer 7 not only on the side surfaces of the light-emitting layer of the light-emitting element 2 but also on the front surface of the substrate below the side surfaces of the light-emitting layer, thereby increasing the thickness of the resin in the reflective resin layer 7 and suppressing light leakage to the back surface of the substrate. This allows for a light-emitting device with good temperature characteristics while more effectively suppressing light leakage to the back surface of the substrate 1.

[0030] Furthermore, when using a light-emitting element (LED chip) with a flip-chip structure as described below, it is necessary to provide a metal pattern 11 printed on the substrate 1. However, since the metal pattern 11 absorbs light, if it becomes possible to provide a thick reflective resin layer 7 on the metal pattern 11, it can be expected that the reflective resin layer 7 will reduce light absorption by the metal pattern 11.

[0031] (light-emitting element) The type of light-emitting element 2 in the light-emitting device according to the present disclosure is not particularly limited. The light-emitting element 2 can be selected from well-known LED chips that emit ultraviolet to blue light, or it can be an LED chip that emits red light. The light-emitting element (LED chip) is preferably a flip-chip type, which has a P-type electrode and an N-type electrode on one main surface and emits light from the other main surface. In an LED chip, light is emitted from the light-emitting layer, not only above and below the LED chip, but also from the sides. When using a flip-chip type, the base portion of the LED chip (the top surface side of the light-emitting element (LED chip) 2) is the light extraction surface, making it relatively easy to ensure the distance in the thickness direction from the light-emitting layer 3 to the light extraction surface. As a result, even if the reflective resin 7 is provided above the side surface of the light-emitting layer 3 to the top surface of the LED chip 2, the reflective resin 7 is less likely to climb up onto the light extraction surface. This makes it possible to stably improve the light extraction efficiency of the light-emitting device.

[0032] There is also no particular limitation on the number of light-emitting elements 2 to be placed inside the openings of the resin wall 4. Although one light-emitting element 2 may be placed in one opening, in the case of placing multiple light-emitting elements 2 in one opening, the effect of heat generated by the light-emitting elements 2 becomes greater, and the effect of the light-emitting device of the present disclosure is more pronounced.

[0033] A buffer film (not shown) for reducing total reflection of light on the side surface of the light-emitting layer 3 may be provided between the reflective resin layer 7 and the light-emitting element 2. Furthermore, something other than the reflective resin layer 7 may be provided between the reflective resin layer 7 and the resin wall 4, between the reflective resin layer 7 and the substrate 1, and / or between the reflective resin layer 7 and the phosphor resin layer 9.

[0034] (Resin wall) The resin wall 4 is formed on the substrate 1 so as to surround the light-emitting element 2. The light-emitting element 2, the reflective resin layer 7, the phosphor resin layer 9, etc. are arranged inside the opening of the resin wall 4. The resin wall 4 is also called a dam or a resin frame. The resin wall 4 can be made of a resin containing a filler that enhances light reflection, such as titanium oxide. The shape and constituent materials of the resin wall 4 are not particularly limited as long as the light-emitting element 2, the reflective resin layer 7, the phosphor resin layer 9, etc. can be arranged in the opening of the resin wall 4.

[0035] 1, 3, and 4, the resin wall 4 preferably includes an opening reduction portion 5 in which the opening dimension of the opening is reduced in the normal direction to the upper surface of the substrate 1 in a cross-sectional view. It is also desirable that a reflective resin layer 7 fills the space between the opening reduction portion 5 and the substrate 1. The anchor effect of the opening reduction portion 5 can stably prevent peeling of the reflective resin layer 7, and the reflective resin layer 7 can be stably disposed on the substrate 1.

[0036] Furthermore, an opening expansion section 6 may be provided above the opening reduction section 5, in which the opening dimension of the opening expands in the normal direction to the upper surface of the substrate 1 in a cross-sectional view. In such a case, the cross-sectional shape of the resin wall 4 may be, for example, a polygonal shape such as a substantially circular, elliptical, diamond, hexagonal, or octagonal shape. Here, the term "substantially" includes a cross-sectional shape that is slightly distorted or partially rounded. Of course, as shown in the light-emitting device 200 of Variation 1 in FIG. 2, the resin wall 4 may be composed solely of the opening expansion section 6, in which the opening dimension of the opening expands in the normal direction to the upper surface of the substrate 1 in a cross-sectional view, or may be a vertical wall with a constant opening dimension. The cross-sectional shape of the resin wall 4 can be adjusted by matching the shape of the nozzle used to extrude the resin to form the resin wall 4 to the cross-sectional shape of the resin wall 4 to be formed. By providing the opening expansion section 6 above the opening reduction section 5, the width of the resin wall 4 can be made relatively narrower and the height of the resin wall 4 can be made relatively taller compared to Variation 1 in FIG. 2. This allows the resin wall 4 to be provided with a thick reflective resin layer 7 while keeping the size of the light emitting device relatively small.

[0037] The resin constituting the resin walls 4 may have a Shore A hardness of 53 to 68. The resin walls 4 are made of a resin harder than the reflective resin layer 7 (the resin of the reflective resin layer 7 is softer than the resin of the resin walls 4). In this case, the difference in Shore A hardness between the resin of the resin walls 4 and the resin of the reflective resin layer 7 is preferably 25 or more, more preferably 35 or more.

[0038] (Reflective resin layer) The reflective resin layer 7 is provided in the space inside (at the opening) surrounded by the resin wall 4 on the substrate 1, and is also arranged around the light emitting element 2. The reflective resin layer 7 according to the present disclosure reflects light from the light emitting element 2 to efficiently guide the light upward, thereby improving the light extraction efficiency, and is made of a resin containing a filler such as titanium oxide that enhances light reflection.

[0039] The reflective resin layer 7 according to the present disclosure may be made of a resin softer than the phosphor resin layer 9, i.e., a resin with a lower Shore A hardness. The softness of the resin of the reflective resin layer 7 may be, for example, in the range of 17 to 26, more preferably 20, in Shore A hardness. The softness of the resin of the phosphor resin layer 9 may be, for example, 26, in Shore A hardness.

[0040] The reflective resin layer 7 improves light extraction efficiency by covering the side surfaces of the light emitting element 2, and by using a soft resin, it is possible to absorb the effects of thermal expansion and contraction caused by the light emitting element 2 that generates heat.

[0041] If the resin of the reflective resin layer 7 is harder than the resin of the phosphor resin layer 9 (the Shore A hardness of the phosphor resin layer 9 is << the reflective resin layer 7), when the light-emitting element 2 reaches a high temperature, heat is transferred to the reflective resin layer 7, and the reflective resin layer 7, which is surrounded by the resin wall 4 and the substrate 1, tends to expand mainly toward the phosphor resin layer 9. At this time, if the hardness of the phosphor resin layer 9 is high, internal stress in the reflective resin layer 7 increases. As a result, peeling may occur at the interface between the reflective resin layer 7 and the light-emitting element 2, starting from the corners or sides of the light-emitting element 2, resulting in a decrease in the light extraction efficiency of the light-emitting device and a bias in the chromaticity distribution. If the difference in Shore A hardness between the resins of the reflective resin layer 7 and the phosphor resin layer 9 is small, or more preferably, is approximately the same, the phosphor resin layer 9 can deform to follow the deformation of the reflective resin layer 7 when the reflective resin layer 7 tries to expand toward the phosphor resin layer 9. As a result, it is possible to prevent peeling from occurring at the interface between the reflective resin layer 7 and the light-emitting element 2, starting from the corners or sides of the light-emitting element 2. Therefore, it is preferable that the difference in Shore A hardness between the resin of the reflective resin layer 7 and the resin of the phosphor resin layer 9 is small, and more preferably, they are about the same. It is preferable that the difference in Shore A hardness between the resin of the reflective resin layer 7 and the resin of the phosphor resin layer 9 (Shore A hardness of the phosphor resin layer - Shore A hardness of the reflective resin layer) is 0 or more and 20 or less, more preferably 0 or more and 18 or less.

[0042] As shown in Figures 1-4, it is preferable to use a light-emitting element 2 with a flip-chip structure, in which the reflective resin layer 7 and the light-emitting element 2 are in contact with each other. Furthermore, by increasing the thickness of the reflective resin layer 7 and reflecting light upward while reducing light leakage to the back side of the substrate 1, the brightness of the light-emitting device in the upper direction can be further improved. In particular, it is more preferable to form the upper surface 7S of the reflective resin layer 7 so that it is higher than the height of the upper surface 3S of the light-emitting layer 3 of the light-emitting element 2 and is thick enough to be equal to or lower than the height of the upper surface 2S of the light-emitting element 2. This allows the reflective resin to reflect light emitted from the side surface of the light-emitting layer 3. Therefore, the brightness of the light-emitting device in the upper direction can be further improved.

[0043] Furthermore, it is desirable that the portion of the reflective resin layer 7 on the light emitting element 2 side be provided to a height that is above the side surface of the light emitting layer 3 and extends to the top surface of the LED chip 2. Furthermore, it is desirable that the portion of the reflective resin layer 7 on the resin wall 4 side be provided to a height that ranges from the height of at least a portion of the opening reduction portion 5 of the resin wall 4 to the height of at least a portion of the opening expansion portion 6 of the resin wall 4. This creates an anchor effect that stably suppresses peeling of the reflective resin layer 7, while reflecting light from the light emitting element 2 and efficiently guiding the light upward, and more effectively suppressing light leakage to the back surface side of the substrate 1.

[0044] The resin constituting the reflective resin layer 7 can be a silicone resin, a hybrid resin having the properties of both a silicone resin and an epoxy resin, etc. The base resin of the reflective resin layer 7 may be selected from resins of the same type as the resin constituting the phosphor resin layer 9 but with different softness (Shore A hardness).

[0045] Furthermore, it is also preferable that the resin of the reflective resin layer 7 be made of a material that is more susceptible to thermal cure shrinkage than the resin of the phosphor resin layer 9. The ease of cure shrinkage can be expressed, for example, by the shrinkage rate at the time of curing, and it is preferable that the shrinkage rate of the resin of the reflective resin layer 7 is greater than that of the phosphor resin layer 9. By using such a combination of resins, a recess (depression) 8 is formed on the upper surface of the reflective resin layer 7, as shown in the light-emitting device 300 of Modification 2 in FIG. 3 and the light-emitting device 400 of Modification 3 in FIG. 4. Since the recess between the light-emitting element 2 and the resin wall 4 is rounded, deterioration of light-emitting characteristics, such as the light emitted from the light-emitting element 2 becoming cross light and being less likely to produce a yellow ring, can be effectively suppressed, resulting in better light-emitting characteristics. Therefore, it is preferable that the reflective resin layer 7 have a recess (depression) 8 on its upper surface.

[0046] (phosphor resin layer) The resin of the phosphor resin layer 9 according to the present disclosure is not particularly limited as long as it satisfies a predetermined softness (Shore A hardness) relationship with the resin of the reflective resin layer 7 and is made of a resin containing a phosphor. The softness of the resin of the phosphor resin layer 9 can be, for example, 15 to 35 Shore A hardness. The resin constituting the phosphor resin layer 9 can be made of a silicone resin, a hybrid resin having the properties of both a silicone resin and an epoxy resin, or the like. The phosphor may contain one or more types of phosphors, such as a YAG phosphor.

[0047] The phosphor resin layer 9 is provided above the light-emitting element 2, and it is sufficient that it covers the output surface of the light-emitting element. As shown in Figs. 1-4, it may be formed so as to cover the entire opening of the resin wall 4. Furthermore, as shown in Figs. 1 and 3, the phosphor resin layer 9 may be in contact with the top of the enlarged opening portion 6, or it may be provided inside the enlarged opening portion 6.

[0048] When a recess (depression) 8 is formed on the upper surface of the reflective resin layer 7, a recess (depression) 10 can also be formed on the surface of the phosphor resin layer 9 above the recess of the reflective resin layer 7, as shown in the light-emitting device 400 of Fig. 4. This structure is more preferable because it further improves the angular color difference. By relatively increasing the adhesion with the reflective resin layer 7, the recess (depression) 10 can also be easily formed on the surface of the phosphor resin layer 9.

[0049] (Lighting equipment) The present disclosure can provide a lighting device including the above-described light-emitting device. FIG. 5 shows an example of a lighting device (top view). Note that the phosphor resin layer is not shown so that components such as the light-emitting element can be seen. It is possible to provide a light-emitting device including a Zener diode 30 and the like in addition to the light-emitting element 2 within an opening in a resin wall 4 provided on a substrate 1, and a lighting device 500 including a diode 31 and an IC 32 on the substrate 1 outside the opening in the resin wall 4. Specific uses of the lighting device are not particularly limited, and it can be used for indoor lighting, outdoor lighting, a headlamp for an automobile, etc.

[0050] As described above, the light emitting device according to the present disclosure is a light emitting device that can suppress changes in light emitting characteristics caused by heat generation in the light emitting element.

[0051] The present specification includes the following aspects. [1]: A light-emitting device comprising: a light-emitting element mounted on a substrate; a resin wall surrounding the light-emitting element; a reflective resin layer provided on the substrate between the resin wall and the light-emitting element; and a phosphor resin layer provided above the light-emitting element, wherein the reflective resin layer is made of a resin softer than the resin wall. [2]: The light emitting device according to [1], wherein the reflective resin layer is made of a resin softer than the phosphor resin layer. [3]: The light emitting device according to the above [1], wherein the difference in Shore A hardness between the reflective resin layer and the phosphor resin layer (Shore A hardness of the phosphor resin layer - Shore A hardness of the reflective resin layer) is 0 or more and 20 or less. [4]: The light-emitting device includes a light-emitting layer that generates light therein; The light emitting device according to [1], [2] or [3] above, wherein the upper surface of the reflective resin layer is higher than the upper surface of the light emitting layer and lower than the upper surface of the light emitting element. [5]: The light-emitting device according to [1], [2], [3] or [4], wherein the reflective resin layer is made of a material that is more susceptible to shrinkage due to hardening caused by heat than the phosphor resin layer. [6]: The light emitting device according to [1], [2], [3], [4] or [5], wherein a recess is provided on the upper surface of the reflective resin layer. [7]: The light-emitting element has a flip-chip structure; The light emitting device according to any one of [1], [2], [3], [4], [5], and [6], wherein the reflective resin layer and the light emitting element are in contact with each other. [8]: A lighting device comprising the light-emitting device according to [1], [2], [3], [4], [5], [6] or [7].

[0052] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Explanation of symbols]

[0053] 1...substrate, 2...light-emitting element, 2S...upper surface of light-emitting element, 3...light-emitting layer, 3S...upper surface of light-emitting layer, 4...resin wall, 5...reduced opening portion, 6...enlarged opening portion, 7...Reflective resin layer, 7S...Upper surface of reflective resin layer, 8...Concave portion (reflective resin layer), 9...phosphor resin layer, 10...recess (phosphor resin layer), 11...metal pattern, 12... junction layer; 13, 14... electrodes; 30... Zener diode; 31...Diode, 32...IC, 100, 200, 300, 400...Light-emitting device, 500...Lighting equipment.

Claims

1. a light emitting element mounted on a substrate; a resin wall surrounding the light-emitting element; a reflective resin layer provided on the substrate between the resin wall and the light-emitting element; a phosphor resin layer provided above the light-emitting element, The light emitting device is characterized in that the reflective resin layer is made of a resin softer than the resin wall.

2. 2. The light emitting device according to claim 1, wherein the reflective resin layer is made of a resin softer than the phosphor resin layer.

3. 2. The light-emitting device according to claim 1, wherein the difference in Shore A hardness between the reflective resin layer and the phosphor resin layer (Shore A hardness of the phosphor resin layer - Shore A hardness of the reflective resin layer) is 0 or more and 20 or less.

4. The light-emitting device includes a light-emitting layer therein that generates light, 2. The light emitting device according to claim 1, wherein an upper surface of the reflective resin layer is higher than an upper surface of the light emitting layer and lower than an upper surface of the light emitting element.

5. 2. The light emitting device according to claim 1, wherein the reflective resin layer is made of a material that is more susceptible to shrinkage due to hardening caused by heat than the phosphor resin layer.

6. 6. The light emitting device according to claim 5, wherein a recess is provided on the upper surface of the reflective resin layer.

7. The light emitting device has a flip chip structure, The light emitting device according to claim 1 , wherein the reflective resin layer and the light emitting element are in contact with each other.

8. A lighting device comprising the light-emitting device according to any one of claims 1 to 7.

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